The invention is directed to a method for helically-shaped binding of round bales of harvested agricultural crops in a round bale press with a first twine cord and with a second twine cord, which are conducted back and forth during the binding process by means of two cord guide members along a slot extending across the width of the press space and which cross over each other prior to being cut off at the termination of the binding process.
The wrapping of round bales must simultaneously fulfill two essential requirements. On the one hand, the round bale must be tightly wrapped a sufficient number of times in order to obtain a cylindrical shape and a high bale strength. On the other hand the wrapping period must simultaneously be shortened and unnecessary wrapping must be avoided whenever possible.
A method is known from DE-OS 34 14 080, in which two twine ropes are used in order to shorten the binding period, which ropes respectively wrap around only a little bit more than half the bale. The binding of the bale begins herein on both sides at a distance from the vertical central plane of the bale, and the twine ropes are introduced with their free ends into the press space and are carried along the bale. During rotation of the bale the two twine cords are initially respectively guided in opposite directions across the center of the bale and outward towards the ends of the bale, where they form several parallel windings. The cords are then conducted inwardly from the outward side towards the center of the bale, where the two twine cords cross and are at the same time cut off respectively by a cutter. This method has the principal disadvantage, that the ends of both twine cords lie completely loose upon the surface of the bale at the end of the binding process. If the bale is rolled on the ground or due to the effect of wind, the two loose ends unravel from the surface of the bale, causing the bindings to loosen in the central bale region whereupon the bale expands in this region so that out of round (conical) bales are formed. The central region of the bale is especially subjected to a high expansion pressure, since the swath which has to be picked up from the ground is more tightly packed in the middle than at the edges.
In another process with two twine cords known from EP-A-0 217 714, the binding starts off center on both sides of the bale. Then the two twine ropes are led a short distance upstream of the respective bale ends, wrapped simultaneously several times around both bale ends at respectively one point and subsequently led back up to a short distance before the center of the bale, where both twine cords form several parallel windings spaced next to each other in order to be then simultaneously cut off. A mutual crossing over of the two twine cords does not occur, so that no interconnection between the bindings of both bale halves exist. At the end of the binding process, two free cord ends lie upon the surface of the bale, which ends can unravel independently of each other. Another disadvantage lies in the higher consumption of twine cord because of the double parallel windings on both sides of the bale middle.